Crushing mill



April 9, 1929. H T B 1,708,195

CRUSHING MILL Filed Dec. 15, 1927 //Vl ENTOR.'

ATTORNEY Patented Apr. 9, 1929.

UNITED STATES ALBERT n. STEBIBINS, or LOS ANGELES, CALIFORNIA.

cnusnme MI LL.

Application filed December 15, 1927; Serial No. 240,151.

This invention relates to crushing mills and more particularly to a novel pi e construction designed for use in conductlng the crushed products from the mill.

Ball mills, rod mills and tube mills are extensively used for crushing ores and various other material, and these crushing mills are frequently so constructed that the crushed products are removed from the crushing chamber by passing air through the mill so that the particles upon being crushed to a. predetermined size will be carried out of the crushing chamber, by the air currents.

The air may be forced through the ball,

red or tube mills by blast means, or it may be sucked through the mills by exhaust means, the latter construction usually being preferred. The use of air to remove the,

crushed products from the type of crushing mills just mentioned is known as air sweeping and the sweeping currents of air have been produced through the mills heretofore by providing a suction fan adjacent the delivery end of the mill.

This arrangement of the suction fan, however, is not entirely satisfactory, because the larger particles exhausted from the mill will rapidly wear out the fan blades if permit-ted to pass through the fan, and difliculty has been experienced heretoforein attempting to remove the larger particles from the air before they reach the fan.

In employing crushing mills of the air,

sweep type it is usual to provide one or more air classlfiers to remove the crushed products from the air exhausted from the mill, and at least, one of these classifiers is commonly mounted above the mill so that the heavier particles removed from the air by the classi- 40 fier may be returned by a gravity feed to the crushing mill-for further treatment.

When the air classifier is placed above the crushing 'mill to secure the return gravity feed just mentioned, it is difficult to prevent I 4 the heavier particles from lodging in the air pipe leading from the exhaust side of the mill to the air classifier, "unless the fan is placed between the mill and classifier, but

this location of the fan, as above pointed out,

is objectionable because of the injurious action of the heavier particles carried by the air upon the fan.

Having in mind the fore oing,

invention relates to means heavier particles from lodging in the air pipe leading the present fer preventing the from the crushing mill, thus making the mill to thegseparator Will be greatest at the elbow or upward bent portion of the pipe, and clogging of the pipe at this point is prevented, in accordance with the present invention, by providing apertures at the bend of the pipe through which jets of air are intro duced to pick up the particles that tend to lodge at the bend of the pipe.

Another feature of the invention resides in the arrangement of the crushing mill, fan, and separators in a closed circuit so that the same air is passed repeatedly through the circuit, and in means for supplying air from the fan to the air apertures provided in the pipe to prevent clogging.

Other features of the invention and novel combination of parts, in addition to the above, will be hereinafter described in connection with the accompanying drawings, which illustrate one good practical form of the invention.

In the drawings v Fig. 1 is a side elevationof a group of cooperating machines connected in a closed circuit;

Fig.- 2 on an enlarged scale is a vertical sectional view through the elbow portion of an exhaust pipe of Fig. 1 showing the air inlet apertures of the present invention; and Fig. 3 is a transverse sectional view of the parts shown in Fig. 2.

The apertured construction of the present invention for preventing particles from lodging in the elbow portion of an air pipe may be employed in various installations, but is particularly well adapted for use in connection with a crushing mill of the air sweeping type such as 'shown in Fig. l of the drawin 'The crushing mill 10 may constitute a ba 1 mill, tube mill or rod mill of wellknown construction and of the air sweeping type in which the crushed particles are removed from the crushing chamber by air currents that are passed through the mill.

In the construction shown the crushing mill consists of a cylindrical tacle 10 having the end flanges 11 and '12.

shaped'recepair within this classifier and collect in the The flange 11 is provided with a hollow trunmen that is journaled' in thesupporting bracket 13 and the flange 12 hasa hollow trunnion that is journaled in the supporting bracket 14; The crushing millis rotated by the ring gear 15 mounted upon the receptacle 10 and which is driven by the pinion 16 secured to the driving shaft 17 having the tight and loose pulleys 18, 19. i

The materials to be treated may be fed to the crushing mill 10 from a bin 20 through a feed pipe 21 that delivers the materials into the feed hopper 22 which directs the materials into the hollow trunnion provided upon the flange 11. The air employed in sweeping the crushed materials from the crushing machine may also be delivered to the receptacle 1( through the feed pipes 21-22, and the flow of air into the receptacle 10 through these pipes will help to carry thelmaterials to be ground into the crushing m1 .Inthe construction shown air is drawn through the crushing mill by a fan'23'which islocated a substantial distance from the millsothat the suction airclassifier 24 of any preferred or well known construction may be interposed between the fan 23 and the material discharge end of the crushing mill 10. The upper end of the air classifier 24 is .connected to the air inlet opening or centre of the fan 23 by a pipe 25 and air is drawn into the classifier 24 from the crushing mill 10 through the upwardly extending pipe 26. I

As a result of the construction just described the heavier particles within the air exhausted from the crushing mill are removed from the air by the classifier 24 before these heavier particles reach the fan 23, and as a result these heavier particles are prevented from passing through the fan and injuring the same. The air classifier 24 is supported above the crushing mill 10 so that the materials which are separated out of the lower portion 27 of the classifier may be returned to the mill for further treatment by a gravity feed. 7

It may be desirable to further cleanse these larger or heavier particles before they are returned to the crushing mill, and this is accomplished in accordance with the present inventlon. by providin an ore screen 28 which is so arranged t at as the materials discharged from the receptacle 27' travel down the inclined apertured surface 29 they will be subjected to the action of rising currents of air which pass upwardly through the-apertured surface 29 to carry off the dust and fine particles which may tend to cling to the heavier particles traveling along the apertured surface 29. The heavier materials upon reaching the lower end of the air screen 28' are delivered by the discharge spout 30 into, the feed pipe 21 so that they will be returned to the crushing mill for further treatment. l

Since the exhaust fan 23 is located a substantial distance from the crushing mill 10 the materials within the'air exhausted from the crushing mill 10 may tend to lodge in the elbowor bent portion 31 of the ipe 26, and if the materials are permitte to accumulate in this elbow they will obviously clog the air exhaust pipe 26 and arrest the.

operatien of the machine. The accumulation of the materialswithin the elbow 31 of the curved wall of the elbow 31. The apertures 32 in most cases should be constructed so that they will introduce air into the pipe 26 in the dlrection'in which the material laden air travels in this pipe, but it may be desirable to provide a few apertures 32 lying near the vertically extendin portion of the elbow 31 so that they willirect jets of air into the pipe 26 in the opposite direction to that in which the material laden air is traveling within this pipe, as will be apparent from Fig. 2 of the drawing. Usually the amount of air it is necessary to direct through the crushing mill 10 to remove the crushed materials therefrom is less than the volume of air required within the exhaust pipe 26 to carry these materials through this pipe into the classifier 24. It is therefore desirable to introduce an additional amount of air into the pipe 26 near the inlet end thereof and the apertures 32 just described perform the double function of supplying this additional amount of air and also of preventing materialsfrom depositing within theelbow 31. The air which is drawn into the pi e 26 through the a ertures 32, may if desired be admitted directly from the atmosphere, but when a closed circuit is employed such as contemplated in the present construction whereby the same air is passed repeatedly through the crushing mill, it is desirable to provide means for supplying air from the exhaust side of the fan 23 to the apertures 32, and this is accomplished, in accordance with the present invention by providing the elbowportion' of the pipe 26 with a receptacle '33 the lower portion of which may have the conical construction indicated by 34 so that the particles which may accumulate in this receptacle will slide down by adjusting an air the inclined walls thereof towards the opening 35 from which they may be withdrawn from time to time. Air is supplied to the receptacle 33 by an auxiliary pipe 36 which in the construction shown leads from a blast air classifier 37 which is connected to theblast side of the fan 23 by the pipe 38. The air classifier 37 may have any preferred or Well known construction and the materials which are removed from the air within this receptacle will pass downwardl into the lower conical end 39 thereof and from which they may be discharged into the product receiving bin 40. The larger portion of the air that 37 is returned to the crushing mill 10 through the air pipe 41, while, as above pointed out, some of the air from the classifier 37 passes through the pipe 36 to the receptacle 33 provided aboutthe' apertured elbow 31. I

The air screen 28 above described is connected to the suction side of the fan 23 by the pipe 42 and since air is drawn continuously into the classifying system from the atmosphere through the apertured surface 29 the volume of air within this entire system will be gradually increased unless means is provided for removing from the system a volume of air substantially equal to that admitted through the apertured screen 29. This is accomplished in'accordance with the present invention by providing an auxiliary ore classifier 43 which is connected to the discharge portion of the air blastclassifier 37 44and the air which is by a branch'pipe. discharged from the auxiliary classifier 43 may escape into the atmos here through the discharge pipe 45 while t e heavier particles which are removed from the air within this auxiliaryclassifier maybe delivered to the product bin 40 through the discharge pipe 46.

It will be apparent from the foregoing that the various'machines described areconnected in a closed circuit so that the same air is passed repeatedly through the different machines of the crushing and classifying unit. The amount of air that is permitted to enter the suction pipe 36 through the apertures 32 may be controlled as desired gate 47 provided upon the air supply pipe 36, and the trouble experiencd heretofore due to the tendency of theparticles to accumulate in the elbow 31v is entirely overcome/through the provision of the air inlet apertures 32.

What is claimed is:

1. In combination with a crushing mill of the air sweeping type, an exhaust pipe leading from said milland having a laterally extending portion and an upwardlyextending portion, exhaust means located a substantial distance above said mill and connected to said pipe to draw the crushed passes through the blast classifier,

products from the mill upwardly through the pipe, and an elbow connecting the laterally and upwardly extending portions of the pipe and provided with air apertures adapted to admit jets of air at the bend of the pipe to pick up the particles that tend to lodge in said elbow.

2. In combination with a crushing mill of the air sweeing type, an exhaust pipe leading from said mill and havinga laterally extending portion and an upwardly extending portion, exhaust means located a substantial distance above said mill and connected to said pipe to draw the crushed products from the mill upwardly through said pipe, an clbow connecting the laterally and upwardly extending portions of the pipe and provided with air apertures adapted to admit jets of air at the bend of the pipe to pick up the particles that tend to lodge at said elbow, a casing enclosing the apertured portion of said elbow, and means for controlling the volume of air admitted into said casing.

3. In combination with a crushing mill of the air sweeping type, an exhaust pipe leading from said mill and having a laterally extending portion and an upwardly extending portion, an exhaust fan for drawing air through said mill and pipe, an air classifier mounted above said mill and connected to said pipe between the mill and exhaust fan, and an elbow connectin the laterally and upwardly extending portions of the pipe and provided with air apertures adapted to admit jets of air into t e pipe at said elbow'.

.4. In combination with a receptacle adapted to contain comminuted particles,'an exhaust pipe leading from said receptacle and having a horizontally extending portion and a vertically extending portion, exhaust means located a substantial distance from said receptacle and connected to said pipe to draw the comminuted particles from the receptacle through said pipe, and an elbow connecting the horizontally and vertically extending portions of the pipe and provided with apertures for admitting jets of air into said pipe at said elbow. V

5. In combination with a receptacle adapted to contain comminuted-1 particles, an ex haust pipe leading from said receptacle and having a horizontally extending portion and a vertically extending portion, exhaust means located a substantial distance from said receptacle and connected to said pipe to draw the comminuted particles from the receptacle throu h said pipe an elbow connecting the horlzontally an vertically 'ex tending portions of the pipe and provided with apertures for admitting jets of air into said pipe at the elbow and adjustable means for controlling the volume of air that enters the pipe through said apertures.

' 6. In combination with a receptacle adapted to contain comminuted particles, an exhaust pipe leading from said receptacle and having a horizontally extending portion and a vertically extending portion, exhaust means located a substantial distance from said receptacle and connected to said pipe to draw the comminuted particles from the receptacle through said pipe, an elbow connecting the horizontally and vertically extending portions of the pipe and provided with apertures for admitting-jets of air into said pipe at the elbow, and blast means for forcing air into the pipe through said apertures. i

. 7. In combination with a crushing mill of the air sweeping type, an exhaust pipe leading from said mill and having a laterally extending portion and an upwardly extending portion, an exhaust fan for drawing air through said mill and pipe and provided with a conduit for returning the air discharged from the fan to the mill in a closed circuit, an air classifier mounted above said mill and connected to said pipe between the mill and exhaust fan, an elbow connecting the laterally and upwardly extending portions of the pipe and provided with air aperturesadapted to admit jets of air into the pipe at said elbow, and means for delivering part of the airdischarged from said fan to said apertures.

8. A crushing mill and air classifier con-' nected to form a closed circuit and including, a crushing mill of the air sweeping type,

an exhaust pipe leading from said mill and having a horizontally extending portion and a vertically extending portion, an exhaust fan for drawing air through said mill and pipe and provided with a conduit for returning the air discharged from the fan to the mill in a closed circuit, an'air classifier connected to said pipe between the mill and exhaust fan, an elbow connecting the horizontally and vertically extending portions of 'said pipe and provided with air apertures adapted to admit jets of air into the pipe at said elbow, and means for conducting part'of the air discharged from said fan to said apertures.

9. A crushing mill and air classifier connected to form a'closed circuit and including, a crushing mill of the air sweeping type, an exhaust pi e leading from said mill, an exhaust fan or drawing air through said mill and pipe and provided with a conduit for returning the air discharged from the fan to the mill in a closed circuit, an air classifier connected to said pipe between the mill and fan to remove the larger particles from the air before they reach the fan and arranged above the mill to return the larger particles tothe mill by gravity, and means for introducing an additional volume of air into said pipe to help carry the materials through the pipe to the classifier.

10. A crushing mill and classifier connect- 'ed to form a closed circuit and including,

a crushing mill of the air sweeping type, an exhaust fan provided with conduits for exhausting air from oneend of the mill and returning it to the opposite end of the mill, a suction ai r classifier connected in the circuit between the mill and fan, a blast air classifier connected in the circuit between the discharge side of the fan and mill, an air screen positioned to receive the heavier particles discharged from the suction classifier and ,adapted to further clean the heavier particles and then'return them to the mill, and an auxiliary classifier arranged to remove from the closed circuit a volume of air corresponding to the volume of air introduced into the circuit by the air screen.

11. A crushing mill and classifier. connected to form a closed circuit and including, a crushing mill of the air sweeping type, an exhaust fan provided with conduits for exhausting air from one end of the mill and returning it to the opposite end of the mill, a suction air classifier connected in the circuit between the mill and fan, a blast air classifier connected in the circuit between the discharge side of the fan and mill, and an auxiliary conduit for conducting part of the air of said circuitfrom the blast classifier to the conduit leading from said mill to increase the carrying capacity of thematerial laden air in said conduit.

In testimony whereof, I have signed my name to this specification. I

ALBERT H. STEBBINS. 

